Control of web elongation



Aug. 15, 1967 c. H. ANGELL 3,335,928

CONTROL OF WEB ELONGATION Filed June 9, 1965 5 Sheets-Sheet 1 ATTOE VE Y;

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C. H. ANGELL CONTROL OF ELONGATION Aug. 15, 1967 Filed June 9,

United States Patent 3,335,928 CONTROL OF WEB ELONGATION Charles H. Angeli, Danville, Ill., assignor to Hurletron Incorporated, Danville, Ill., a corporation of Delaware Filed June 2 1965, Ser. No. 462,616 Claims. (Cl. 226-39) ABSTRACT OF THE DISCLOSURE Apparatus for regulating by two modes the tension on a continuously moving stretchable web such that web registration is maintained despite cumulative as well as noncumulative registration error producing conditions. Noncumulative errors are compensated by bidirectionally driven web loop regulating means comprising a plurality of tubular members. One form of the invention employs I a single tubular member having an axis laterally driven This invention relates to the control of elongation in a running web of stretchable material such as paper, paperboard, plastic, film, fabric, metal foil and the like and in laminates of such materials. It is particularly useful in the graphic arts as applied to such operations as printing, embossing, laminating cutting creasing and the like wherein one or more repetitive patterns of work are applied to the moving web over a predetermined length While the material is held under stress or tension.

In operations of the type above mentioned, one object of the invention is to maintain the desired repeat length in the pattern of work applied to the web. This is accomplished by regulating the tension or longitudinal stress in the running web as the work is applied thereto and thus control the elongation or stretch imparted to the web.

The elongation in a web of stretchable material is a function of numerous factors including its structure, caliper or thickness, moisture content, the ambient temperature and relative humidity and the stress under which the material is held. Of these factors, the one which can be most readily and precisely regulated in a running Web is the tension or stress to which it is subjected. This has long been known and used in multi-color printing operations to adjust the repeat length on the web over which separate patterns of color printing are successively applied and keep the several patterns in register (i.e., in proper space relationship to each other on the Web). The same principle has also been used in cutting, creasing, laminating, perforating, punching and similar operations of the type previously mentioned.

The art is replete with letters patent and other literature on the automatic control of color-to-color register, register between printing and cutofi, punching, perforating and the like. Although, in some instances, provision is made for altering the rotational position of one or more work performing member in relation to another; to change the effective distance therebletween along the path of travel of the web, the most common practice is to use a web compensator which is moved in response to minor register variations and changes the length of web between the successive operations to be controlled. Such compensators have a limited range of travel, and with their associated idler rollers, form a web loop of variable length, limited by the range of travel of the compensator roller.

By measuring register and tension variations and recording these variations side by side on a single chart, it has been observed that when a web compensator is moved the first change to occur in the web is an increase or decrease in tension, depending upon the direction in which the compensator is moved. Following this tension change there will be a noticeable change in register between the pattern or work applied upstream along the web from the web compensator and the pattern or patterns applied downstream from the compensator. This register change is progressive and of diminishing magnitude in the successive downstream operations and may progress at a rate exceeding the speed of the web.

In such operations as multi-color printing, proper movement of a web compensator between two successive color printings may and frequently does accomplish a rapid and relatively permanent correction in the register between these successive printings. Subsequent errors in register may occur in either direction and require corrective action by the compensator, but normally the errors are not of a cumulative nature which requires continuous corrective action in one direction. This is also generally true in multiple in-line operations involving such work as printing, cutting, creasing, perforating, punching, embossing and the like when the several rotational work performing members are properly sized in relation to each other. This is because the register changes normally encountered are the result of a change in the length of web between successive operations due to a change in one or more of the factors above mentioned, such as the moisture content, structure, caliper or temperature of the running web.

There is another type of operation in which a web whereon a successive pattern of work has been applied in one machine is rewound and the rewound roll is transferred to another machine in which one or more additional successive patterns of work are applied to the web as it is unwound from the transferred roll. One good example of such an operation is the in-register insetting of a preprinted web in a newspaper press. Here a web which has been preprinted, usually on one side in a rotogravure or offset press is rewound and subsequently fed into a newspaper press wherein additional printing is applied to one or both sides of the web.

The in-register insetting operation in the newspaper press involves the problem of holding the preprinting and the newspaper printing in relatively fixed and proper space relationship on the newspaper page, so that the preprinted pattern does not creep forward or back in relation to the printed pattern applied in the newspaper press. If this proper relationship is not maintained the preprinted pattern will fall in random relationship to the subsequent cutting and folding of the newspaper page. Thus an illustration or text applied in the preprinting operation may be cut at any point within the repeat length of the preprinted pattern and its appearance thus mutilated. To avoid this the preprint is produced to a repeat length slightly shorter than that of the newspaper printing. This shortage may be, for example, .005" to .080" per repeat for a newspaper. of conventional page length. Then, in

the insetting operation, sufficient tension is applied to the web entering the newspaper impression to stretch it and match the repeat length of the preprinted pattern to that of the printing done in the newspaper press. Thus, the separate printings are held in page register and subsequent cutting and folding in the newspaper folder is maintained in the same space relationship to the preprinted pattern as to the pattern of printing applied in the newspaper press.

Another operation of the same general type as in-register insetting involves preprinting and rewinding of one web followed, in a separate operation, by lamination of the preprinted web with one or more additional webs and the performance of additional work, such as slitting, cutting and creasing, for example, on the laminated web. Here the problem is similar to that of in-register insetting and involves performing the secondary operation or operations on the laminated web in register (i.e., proper space relationship) with the preprinted pattern. Again, the best practice is to make the repeat length of the preprinted pattern slightly short of the repeat length of the subsequent patterns of work applied to the laminate and stretch the preprinted web, as it is laminated, to match its repeat length to that of the subsequently applied patterns.

In insetting and laminating operations such as above outlined a continuous correction is required since any consistent error between the repeat length of the preprint and that of the subsequent operations is cumulative. Thus, in insetting, for example, if the repeat length of the preprint is consistently short of the repeat length of the newspaper printing by only .005" per page, the preprint pattern will be displaced from its desired position on the page by 5" in one thousand copies. At modern newspaper press production rates of 50,000 to 70,000 copies per hour this 5" error in page register can occur in approximately one minute of operation. In two minutes the error would be twice as great and so on until the preprint has crept the entire length of the page and continued on another, correspondingly progressive displacement.

Obviously, because of the cumulative nature of the register error encountered in laminating, insetting and similar operations of this general type, involving the application of two or more patterns of work to the web in separate operations which are not in-line or interconnected, the use of a web compensator of the type used to control color-to-color register, for example, gives inadequate results because it quickly runs out of any reasonable range of travel and can make no further correction without stopping the press, pulling the preprinted web up into proper register with the newspaper printing, replacing the compensator at the other extreme of its travel and starting over again. This would occur every few minutes of normal press opertaion and hamper production to the point of practical impossibility.

For the reasons above explained, corrective action on the web in insetting operations is currently accomplished by inducing controlled and continuous resistance to the forward movement of the preprinted Web. This exerts controlled and continuous tension or stress in the web, causing it to stretch by the amount required to match the average repeat length of the preprinted pattern entering the newspaper impression to that of the newspaper printing. Several methods, which are different in operation but alike in intended function have been employed to do this.

One of the first in-register insetting systems, employed extensively in England and on the European continent, involved the use of infeed or pull rolls having a grip on the web and driven through adjustable epicycle gearing at a peripheral speed slightly less than that of the newspaper printing cylinders.

The method employed most widely in the United States involves the use of a vacuum chamber having a perforate surface over and in contact with which the preprinted web passes prior to entering the newspaper impression. By regulating the sub-atmospheric pressure maintained in the vacuum chamber the tension induced in the web is adiusted to whatever value is required to keep the preprinted pattern in proper page register with the newspaper printing.

Another method which has been used to some extent utilizes either the fixed or running belts normally employed in the reel of a newspaper press. These belts bear against the unwinding roll of preprint, offering resistance to its rotation and inducing tension in the web entering the newspaper impression. Regulation of the belt tension or speed, as the case may be, depending upon the type of reel employed, causes more or less tension or stressing in the running web and determines the extent to which the preprinted repeat length is elongated.

The most complex and costly system to build and install is that using the infeed rollers. The simplest and cheapest is the belt tension system, but it has the distinct disadvantage that it undertakes to control the speed of the rapidly unwinding roll of preprint which has considerable mass and inertia at the start of a new roll but diminishes in diameter and in surface contact with the belts as it ex pires, while its rotational speed is increasing for a given linear web speed. These variable factors of mass, roll diameter and speed make this system one in which it is difficult and sometimes impossible to obtain adequate and sufiiciently rapid control of the preprint stretch and repeat length. The system employing vacuum to induce tension and stretch in the web is much less costly to build, install and maintain than the pull roll system and avoids the inherent difficulties of the belt tension system in that it operates on the running web, which has consistent, relatively low mass and inertia at any given press speed. It is by far the most popular and widely used system in current use because of the consistently good control which it provides.

In one specific embodiment the present invention provides a fourth system of in-register insetting, similar in function to the other three but having distinct advantages over each of them. Instead of a vacuum chamber, pull rolls or belts the present invention, as applied to in-register insetting and similar operations, employs a novel and advantageous form of web compensator which induces two types of corrective action in the running web. One is a rapid and, when required, extensive change in web length corresponding to that obtainable with web compensators of the type used in controlling color-to-color register. The other is a more permanent change in web tension which, like that provided in the pull roll or vacuum systems, persists and corrects for the cumulative error in page register until conditions in or on the web again change and require the establishment of a new tension level.

The novel and advantageous features of the invention can best be understood with reference to the accompanying drawing.

FIG. 1 of the drawing is a diagram showing a side elevation of a newspaper reel, printing unit and associated folder employing the features of the invention as applied to in-register insetting.

FIG. 2 is an enlarged, more detailed view of the novel form of web compensator shown in FIG. 1.

FIG. 3 is an elevational view of a modified form of web compensator embodying features provided by the invention.

FIG. 4 is an end view of the compensator mechanism shown in FIG. 3.

FIG. 5 is a cross sectional view through a portion of the compensator shown in FIGS. 3 and 4. It may be considered as taken through the plane indicated at 5-5 in FIG. 3 but shows the toggle assembly of the compensator in a different position than in FIGS. 3 and 4.

It should be understood that, while an in-register insetting operation has been chosen to illustrate the features and advantages of the invention, the novel method and means provided by the invention for inducing substantially simultaneous, dual corrections in a running web of stretchable material have numerous other specific applications, particularly in laminating, cutting, creasing, folding, embossing, perforating, blanking and forming, multi-color printing and the like. The problems normally encountered in each of these operations and various combinations thereof are well known by those familiar with the graphic arts and the manner in which the features of the invention may be utilized to advantage in operations other than in-register insetting will be apparent.

Referring now to FIG. 1 of the drawing, a reel of the newspaper press is shown at 1 and in this particular case is of the type which handles three rolls of paper. A roll 2 of preprinted paper is being unwound while a fresh roll awaits use at 3 and the core of an expired roll at 4 is ready to be replaced with another fresh roll. The stationary belts 5 are anchored at 6 and are held under tension by the belt wheels 7 attached to suitable tension adjusting means not shown, such as a torque motor.

Preferably, in the insetting operation the belts 5, which retard rotation of the unwinding roll of preprint, are held under only suificient tension to prevent the roll from overunning and coasting when the speed of the press is rapidly reduced. This may be 50% or less of the belt tension normally carried on the white roll of paper employed when preprint is not being inset into the press.

The preprinted web being unwound from roll 2 passes, as shown at 8, about the idler rollers 9, 10 and 11 into the first-side printing impression 12 between the plate cylinder 13 and the impression or blanket cylinder 14 which are driven in unison by suitable means not shown and propel the web forward. The web 8 is then directed over idler roller 15 into the second-side printing impression 16 between plate cylinder 17 and blanket cylinder 18 which are like cylinders 13 and 14 and are likewise driven in unison with each other and with the cylinders of the first-side impression.

Assuming that only one side of the web has been preprinted, as is usually the case, and that the preprinted side is wound in on roll 2, additional printing may be applied, when desired to the preprinted side in impression 16, while printing is applied to the opposite or blank side of the preprinted web in impression 12 to com plete the newspaper page or pages from this particular unit of the press.

Normally several additional printing units, each supplied with paper from its own reel, are employed to make up the completed newspaper. The completely printed Web 8 from the printing unit shown, comprising impressions 12 and 16, passes about the rollers 19', 19a, 20 and 19b to a driven roller called the roller-top-of-former and shown at 21. Here the web 8 is combined with other webs such as indicated at 22, 23 and 24 from other printing units of the same newspaper press.

Trolleys 25 are brought to bear on the webs passing over roller 21 to hold them in contact with the latter and help propel them forward over the former board 26. When, as usually is the case, some or all of the webs supplied to the folder are of greater width than two newspaper pages, the webs of three or four page width are slit as they pass over roller 21 into individual ribbons of double or single page width by means of suitable rotary slitting knives, not shown. The two page ribbons are folded transversely in passing over former board 26 and pass between a pair of driven nippling rollers, one of which is shown at 27, to the cutting cylinders 28 where the webs are cut in unison to the desired page length.

In a newspaper of regular size, rather than tabloid size, the cut pages are again folded in the middle, by well known means not shown, to form the completed newspapers which are delivered from the folder to a suitable conveyor, not shown, for transportation to the mailing room.

The operation so far described is conventional except for the use of a preprinted web and except that, in conventional operation, a floating roller 29 which pivots about axis 30 is normally employed to take any slack out of the web passing from the reel to the impressions. The dotted lines 8' show how the web may be passed about floating roller 29. Suitable weights, such as indicated at 31, are usually attached to the rotatable pivot shaft 30 to increase or decrease the effective weight of roller 29, depending upon the position of the weights. Any

movement of roller 29 in the arc indicated by the arrows is normally translated, by suitable and well-known means not shown, into increased or decreased tension on the belts 5, putting greater or reduced drag on roll 2 and allowing it to speed up or slowing it down, as the case may be, until the floating roller 29 is returned to its normal position.

For reasons which will be explained later, the floating roller 29 is preferably by-passed in the insetting operation now to be described and the belts 5 are held under relatively fixed tension which, as previously indicated, is preferably less than the average tension normally carried in a conventional, non-insetting operation.

In accordance with the features of the invention, a novel type of web compensator, is employed to match the repeat length of the preprinted pattern on web 8 to the repeat length of the newspaper printing.

As shown in FIGS. 1 and 2 the compensator comprises tubular members 33, 34 and 35 with member 34 mounted, by means of the threaded member 36-, on screw 37 which is rotatable to move member 34 from the position shown by the solid lines to that shown by the dotted lines and designated in the drawing as 34'. Such movement of memb r 34 causes it to extend the path of travel of web 8', as indicated by the dotted lines 8 in FIG. 2, forming a web loop of adjustable length between the members 33 and 35.

Preferably member 34 is free to rotate on suitable bearings provided at 38, about shaft 39' within the opposite ends of member 34, thus acting as an idler roller propelled by the forward movement of web 8. Member 33 and 34 may be similarly mounted on bearings, but provision is made for locking either or both of these members, when desired, to their mounting bracket 40 by the retractable pins 41 which extend through the bracket into an opening provided in the end caps of members 33 and 34. A more detailed view of similar locking pins is shown in FIG. 3.

With pins 41 locking one or both of members 33 and 35 and preventing rotation thereof the locked member or members offer frictional resistance to movement of the -web thereover and the amount of such resistance will vary in direct relation to the amount of wrap taken by the web about the stationary surface of these members. Thus, as idler roller 34 moves into interference with the web 8 to form loop 8', two types of corrective action take place in the web. The distance which the web travels from the preprinted roll to the newspaper impression is increased as the length of web loop 8 increases. But since the web is restrained from slipping by the nip at the impressions and by the belts on the preprinted roll, the web stretches and the preprinted pattern which it carries is correspondingly elongated. This action takes place rapidly and brings about a substantially instantaneous correction between the position of the preprinted pattern and that of the newspaper printing. However, this action is not of a permanent nature. Once movement of idler 34 is stopped, the change in tension which it exerted on the web does not persist but tends to return to its previous value, other factors being equal. This is known from the previously mentioned graphs which have been made of tension and register changes. Thus to maintain a relatively permanent correction such as required for insetting, in the absence of any other corrective action it would be necessary to keep moving roller 34 until it finally reached the end of its travel. Continuous corrective action would then cease and the insetting operation would be out of control.

The additional action of the type of compensator provided herein is as follows: As the length of the Web loop is altered by movement of roller 34 in either direction, the wrap of the web about members 33 and 34 is changed, bringing a greater or lesser amount of frictional surface into contact with the web. Thus as loop 8 is extended the web encounters greater resistance to its forward travel and the tension or stress in the web is increased. This causes elongation of the web and lengthens the preprinted pattern which it carries. The reverse occurs when roller 34 is moved in the opposite direction to shorten loop 8. This type of corrective action is of a permanent nature, persisting after movement of roller 34 is stopped, and brings about the kind of corrective action ultimately required for in-register insetting.

To summarize, it will be apparent from the foregoing that the type of web compensation provided by the invention brings about a rapid but transitory correction in register as well as a somewhat slower acting but persistent correction. For ony given position of roller 34, the web wrap about the stationary, friction inducing members is fixed and the tension and elongation in the running web remain constant until some other change occurs in the web such as, for example, a change in its moisture content or in the repeat length of the preprinted pattern in the unwinding roll. When this occurs further movement of roller 34, in the proper direction, will bring about the required correction for the conditions which then exist.

Movement of roller 34 is accomplished, in the case illustrated in FIGS. 1 and 2, by the operation of motor 42, which can be actuated to rotate in either direction. The motor shaft 43 carries a worm 44 meshed with worm gear 45 which is attached to one end of the screw 37. Thus, the rotation of motor 42 in one direction causes roller 34 to advance, by the action of the rotating screw 37 in the threaded member 36, extending the web loop and increasing the wrap around members 33 and 35. R- tation of the motor in the opposite direction similarly causes retracting of roller 34, shortening the web loop and the wrap around members 33 and 35.

It will be understood that the members 36, 37, 38, 3?, 4-0, 43, 44 and 45, as well as the bearing brackets 46, the thrust bearings 47 and thrust collars 48 are duplicated at the opposite end of the view shown in FIG. 2, so that roller 34 is moved uniformly at its opposite ends. A single motor 42 is preferably used however, and no duplication of the pins 41 is necessary.

Returning now to FIG. 1, any of the several well known and commonly used forms of automatic control equipment may be used to detect errors in register between the preprint and the newspaper printing and bring about the operation of the compensator motor 42 in the direction and to the extent required to hold the preprinted pattern in proper, relatively fixed position as the newspaper page. Preferably, because of its superior performance as compared with other systems, that disclosed in the United States Letters Patent 3,120,181 is employed and this is the type of detection and automatic control equipment illustrated in FIG. 1. As here used it comprises a photoelectric scanner 50, a photoelectric cylinder position monitor 51 and a control console 52 containing an electronic comparator amplifier 53, utilizing the dual channel circuitry described in said patent, and a power supply circuit 54.

To outline the functioning of the control equipment, scanner 50 detects the occurrence of repetitive register marks printed one repeat length apart in the preprinted pattern carried by the web, generating an abrupt electrical signal which is preamplified in the scanner and transmitted to amplifier 53 through a shielded cable indicated by the broken line 94.

The monitor 51 is coupled to one of the printing cylinders (cylinder 18 in the case illustrated) and a portion of its internal mechanism rotates in unison with each of the cylinders, since the latter are geared together. It is also permissible to drive the internal rotating portion of the monitor from the main press drive shaft, providing suitable gearing is employed therebetween to give the monitor the same rotational speed as the cylinders. Electrical signals generated as described in the aforesaid 8 patent, are transmitted from the monitor to amplifier 53 by another shielded cable indicated at 55.

In the amplifier 53 the signals from the scanner are further amplified and compared to derive an output signal having a voltage indicative of the direction and amount by which the preprinted pattern on the web is out of register with the newspaper printing applied in the newspaper impressions by cylinder 13, cylinder 17 or both.

In the forementioned patent, the mechanism shown for driving the web compensator is hydraulic. An hydraulic motor or cylinder may likewise be employed with the compensator provided by the present invention, but preferably it is driven by an electric motor.

To take full advantage of the nature of the output or command signal from the preferred type of amplifier employed it is most convenient to use a direct current motor in which variable voltage is applied to the armature to regulate its speed, the motor having a permanent magnet field.

Suitable line current (i.e., v., single phase, 60 cycle) is supplied to the power supply circuit 54 in console 52 through the line indicated at 56 to derive all special voltages used in amplifier 53 as well as the filament voltages for the light sources in the photoelectric scanner and cylinder monitor.

The output signals from amplifier 53 are of the same type as those derived in the amplifier disclosed in said patent but, from this point on are handled in a difiierent manner, also well known per se, to obtain suitable power for the motor 42. The additional equipment required may be housed, when desired, in the control console 52 but for better clarity is shown separately in the drawing. This equipment consists first of a transistorized push-pull circuit 58 to which the output signals of amplifier 53 are supplied through a two wire cable 57, the polarity of the current in the two wires being reversed as the direction of the required register correction changes. From the circuit 58 are derived signals suitable for energizing the control winding of a conventional magnetic amplifier 60, to which they are supplied through another two wire cable 59.

Power is supplied to the magnetic amplifier 60 through a three wire cable 61 and is of the conventional single phase, 3 wire system in which the voltage across two of the wires is 240 volts, 60 cycle and that between either of these two wires and the third wire is volts, 60 cycle. The magnetic amplifier output current is supplied through a three wire cable 63 to a silicon controlled rectifier circuit 64, whereto the same type of power input is supplied from cable 61 through cable 62.

The combination of elements 58, 60 and 62 give fullwave-rectified, direct current for operation of the reversible motor 42 from the output signals of amplifier 53. When there is no error in register no output signal is generated in amplifier 53 and no current is supplied to the motor, which remains stationary. When a relatively small error is detected the voltage output from amplifier 53 is low and, consequently, the current to the motor armature is of low voltage and operates the motor at slow speed. If the register error increases, demanding more and faster corrective action at the motor, the output voltages from amplifier 53 and from 64 increase by a substantially proportional amount and operate the motor at higher speed. Thus, full advantage is taken of the detection, amplification and power supply system disclosed in the aforesaid patent to obtain corrective action on the web in the proper direction and at a rate substantially proportional to the error in register to be corrected.

With reference now to FIGS. 4 and 5, which illustrate a modified form of the type of compensating device provided by the invention, the idler 70 (see FIG. 4) may occupy susbtantially the same position on the press as idler 10 of FIG. 1. After passing around idler 70 the web 8 is directed past or around members 71 and 72, depending upon the orientation of the arms 73 to which the shafts 9 74 and 75 of members 71 and 72, respectively, are attached.

The arms 73, which separate and rigidly support members 71 and 72 are mounted on and pivot with shafts 76 which are journaled in the bearings indicated at 77. Pivotal movement of the assembly comprising members 71 to 76 inclusive is accomplished, in the case here illustrated, by rotation of the electric motor 78 which may be of the same type as that described in connection with FIGS. 1 and 2.

The extensions 79 of the double shaft 80 of the motor are connected at their opposite ends to input shaft 81 of worm gear reducers through suitable right angle gearing, one form of which is indicated at 82. Shaft 83, which is journaled in bearing 84, connects one of the bevel gears 82 to input shaft 86 of the gear reducer through a suitable coupling 85. The worm 87 on shaft 86 meshes with and drives the worm gear 88, which is connected to and turns the pivot shaft 76 through the gear reducer output shaft 89 and coupling 90 (see FIG. 3).

As is the case with members 33 and 35 of FIGS. 1 and 2, the rollers 71 and 72 of FIGS. 3, 4 and 5 may, when desired be prevented from rotating on their own axes by engaging the retractable pins 91 with the plates 92 each of which is provided with an opening for the reception of one end of the pin. Suitable detents are preferably provided, as indicated at 93, for retaining the pins in either an extended or a retracted position.

Any other suitable means of releasably locking members 71 and 72 to one of the arms 73 may be employed within the scope of the invention. Such other means may comprise, for example, serrated washers or frictional or magnetic clutch members, one of which is secured to the member to be locked and the other to the arm 73. The invention also specifically contemplates provision for remotely actuating one of the clutch members of each pair (one pair for each of the members 71 and 72) to retract it or bring it into engagement with the other member of the pair. Using magnetic clutches this simply involves the use of a remote switch to make and break the electrical circuit. With a mechanical clutch, an electrical solenoid or a pneumatic or hydraulic cylinder may be used for the same purpose, with a remotely operated switch or valve, as the case may be.

FIG. 5 shows the assembly comprising members 71, 72 and 73 oriented to bring the members 71 and 72 into substantial engagement with the web 8, elongating its path of travel and offering substantial frictional resistance to its forward movement. The members 71 and 72 may be moved, by operation of the compensator motor, from complete non-engagement with the web, as shown in FIG. 4 to even greater interference than that shown in FIG. 5 and, of course, members 71 and 72 may assume any intermediate position required to impart the required register correction.

When neither of the members 33 and 35 of FIGS. 1 and 2 are not prevented, as previously described, from turning on their own axes they act as idler rollers. The same is true of members 71 and 72 of FIGS. 3, 4 and 5. In such instances these members, while free to rotate, propelled by passage of the web thereover, offer some resistance to movement of the web and induce some stress or tension therein. However, when one or both of these members is locked to the connecting arms and prevented from turning on its own axis, they act as drag bars and afford much greater resistance to forward movement of the web. Therefore, the provision for locking these members or freeing them to rotate affords a wide latitude of control over the stress of tension exerted in the web.

When only relatively low web tension is needed to match the repeat length of the preprint to that of the newspaper printing both rollers may be left free to rotate. For intermediate tension levels one of the rollers may be locked and where high tension levels are required'both may be locked. This, in addition to the changes in tension obtained by movement of the compensator to increase or decrease the wrap plus the immediate action resulting from changing the length of the path of web travel by movement of the compensator, gives the system exceptional flexibility.

Although not illustrated in the drawing, the invention also contemplates the use of variable, controlled resistance to rotation of any or all of the members 33 and 35 of FIGS. 1 and 2 or 71 and 72 of FIGS. 3, 4 and 5. This may be accomplished, for example, by inserting a magnetic particle clutch (used as a brake) in the shafts connecting these members to one of their associated supporting arms and varying the control current to the clutches to suit requirements. Other suitable means of accomplishing the same objective will be readily apparent. The invention further contemplates, when desired, the use of a cooling medium within any of the tubular members which do not rotate on their axes. This is common practice in chill rolls used on some presses and will be well understood by those familiar with the art, without illustration. Water is the preferred cooling medium and its circulation through the tubular member or members if preferably controlled, in the present invention, in response to a surface temperature measurement made on the cooled member to keep it slightly above the dew point of the ambient atmosphere, so that it will not'sweat and damage the web.

I claim: 1. In an operation of the type wherein a web of flexible material carrying a preapplied repetitive pattern of work is supplied from a roll thereof to a locus in which another repetitive pattern of work is applied to the web in predetermined and substantially fixed space relation to said preapplied pattern, an apparatus including means for detecting deviations from the desired predetermined space relation and deriving therefrom electrical signals indicative of the directionand extent of the deviations, and an improved means of effecting rapidcor'rctioh of the detected deviations which comprises, in combination: a web compensator having a plurality of tubular members spanning the web width and disposed in spaced relation to each other and in contact with the web at a location between said roll and said locus,

means connected with at least one of said tubular members for changing their relative positions in a manner whereby any such change alters both the length of the path of web travel about said members and their are of contact with the web, means connected with the tubular members for retaining them at any relative position resulting from such change regardless of changes in web tension, and

means responsive to the electrical signals derived from said detected deviations for effecting the changes required in the relative positions of said tubular members to correct the deviations, a momentary correction being obtained by the resulting change in the length of said web path and a persistent correction, for deviations which would otherwise be cumulative, being obtained by the change in said are of contact and the resulting change in web tension.

2. The apparatus defined in claim 1 which further comprises:

means connected with at least one of the tubular members for restraining it from rotation about its longitudinal axis, whereby the tension which it exerts in the web changes in direct relation to alterations in its arc of contact with the web.

3. The apparatus defined in claim 1 in which at least a second of said tubular members has a fixed axis of rotation, and further comprising,

means connected with said second tubular member for selectively inhibiting its rotation, whereby the tension it exerts upon the web changes in direct relation to its arc of contact with the web.

4. The apparatus defined in claim 1 in which two of said tubular members have their longitudinal axes parallel andsupported by means pivotal about an axis parallel to and disposed between said two tubular members and said relative position changing means is coupled to said support means for inducing a pivoting thereof.

5. The apparatus defined in claim 4 which further comprises:

means connected with at least one of said two tubular members for selectively inhibiting its rotation, whereby the tension it exerts upon the web changes in direct relation to its arc of contact with the web.

6. In an in-resetting operation wherein a web of paper carrying a preapplied, repetitive pattern of printing is continuously supplied from a roll thereof to a printing unit in which at least one additional, repetitive pattern is applied to the web, it being required for successful operation to maintain proper register between the separately printed patterns, and wherein an apparatus employed includes means detecting register errors and deriving from such detection electrical signals indicative of the direction and extent of the errors, an improved means of effecting register error corrections which comprises the combination of:

a web compensator having a plurality of tubular members spaced apart, spanning the web width and disposed in contact with the web between said roll and said printing unit,

lei-directional motivating means comprising a portion of the compensator mechanism for changing the relative position of the tubular members in a manner whereby any such change alters both the length of the path of web travel between said roll and said printing unit and the arc of contact between the web and said tubular members,

means connected with the tubular members for retaining them in any relative position to which they are driven by said motivating means regardless of changes in web tension,

means connected with at least one of said tubular members restraining it from rotation about its longitudinal axis, whereby the tension which it exerts in the web changes with alterations in its arc of contact with the web, and

means responsive to said electrical error signals and connected with said motivating means for energizing the same to eiiect the changes required in the relative position of said tubular members for correcting said register errors, a momentary correction which does not permanently alter web tension being obtained as a result of altering said web path and a persistent change in web tension, to correct for register errors which would otherwise be cumulative, being obtained as the result of altering said arc of contact between the web and the restrained tubular member.

7. A web compensator positioned in the path of travel of a running web of stretchable material and constructed and arranged to provide two types of corrective action to the web, said compensator comprising:

5 a pair of tubular members spaced apart with their longitudinal axes parallel and supported at their opposite ends on arms which are mounted to pivot about an axis parallel to and disposed between the tubular members,

positive drive means connected to said arms for pivoting the latter to bring the tubular members into variable degrees of engagement with the web and thereby simultaneously alter the length of the path of web travel about the tubular members and the arc of contact between said members and the web,

means connected to said arms for retaining them in any selected pivotal position regardless of changes in the web tension, and

means connected to at least one of said tubular members for restraining rotation thereof about its longitudinal axis, whereby the tension which it exerts in the web changes with said are of contact,

8. The web compensator as defined in claim 7 in which said compensator is also positioned between an unwinding roll of said stretchable material and a locus wherein a repetitive pattern of work is applied to the web, and

said positive drive means includes reversing means for incrementally pivoting said arms into a plurality of retainable pivotal positions.

9. The web compensator as defined in claim 7 wherein one of said tubular members is journaled for rotation about its longitudinal axis and is free to rotate, while the other tubular member of the pair is restrained from such rotation.

10. The web compensator as defined in claim 7 wherein each of said tubular members is journaled for rotation about its longitudinal axis and wherein releasable means are provided for selectively restraining such rotation of each member.

References Cited UNITED STATES PATENTS M. HENSON WOOD, JR., Primary Examiner.

J, N. ERLICH, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 ,335 ,928 August 15 1967 Charles H. Angell It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 11 line 15 for "in-resetting" read in-register insetting Signed and sealed this 22nd day of October 1968 (SEAL) Attest:

EDWARD J. BRENNER Edward M. Fletcher, Jr.

Commissioner of Patents Attesting Officer 

1. IN AN OPERATION OF THE TYPE WHEREIN A WEB OF FLEXIBLE MATERIAL CARRYING A PREAPPLIED REPETITIVE PATTERN OF WORK IS SUPPLIED FROM A ROLL THEREOF TO A LOCUS IN WHICH ANOTHER REPETITIVE PATTERN OF WORK IS APPLIED TO THE WEB IN PREDETERMINED AND SUBSTANTIALLY FIXED SPACE RELATION TO SAID PREAPPLIED PATTERN, AN APPARATUS INCLUDING MEANS FOR DETECTING DEVIATIONS FROM THE DESIRED PREDETERMINED SPACE RELATION AND DERIVING THEREFROM ELECTRICAL SIGNALS INDICATIVE OF THE DIRECTION AND EXTENT OF THE DEVIATIONS, AND AN IMPROVED MEANS OF EFFECTING RAPID CORRECTION OF THE DETECTED DEVIATIONS WHICH COMPRISES, IN COMBINATION: A WEB COMPENSATOR HAVING A PLURALITY OF TUBULAR MEMBERS SPANNING THE WEB WIDTH AND DISPOSED IN SPACED RELATION TO EACH OTHER AND IN CONTACT WITH THE WEB AT A LOCATION BETWEEN SAID ROLL AND SAID LOCUS, MEANS CONNECTED WITH AT LEAST ONE OF SAID TUBULAR MEMBERS FOR CHANGING THEIR RELATIVE POSITIONS IN A MANNER WHEREBY ANY SUCH CHANGE ALTERS BOTH THE LENGTH OF THE PATH OF WEB TRAVEL ABOUT SAID MEMBERS AND THEIR ARC OF CONTACT WITH THE WEB, MEANS CONNECTED WITH THE TUBULAR MEMBERS FOR RETAINING THEM AT ANY RELATIVE POSITION RESULTING FROM SUCH CHANGE REGARDLESS TO CHANGES IN WEB TENSION, AND MEANS RESPONSIVE TO THE ELECTRICAL SIGNALS DERIVED FROM SAID DETECTED DEVIATIONS FOR EFFECTING THE CHANGES REQUIRED IN THE RELATIVE POSITIONS OF SAID TUBULAR MEMBERS TO CORRECT THE DEVIATIONS, A MOMENTARY CORRECTION BEING OBTAINED BY THE RESULTING CHANGE IN THE LENGTH OF SAID WEB PATH AND A PERSISTENT CORRECTION, FOR DEVIATIONS WHICH WOULD OTHERWISE BE CUMULATIVE, BEING OBTAINED BY THE CHANGE IN SAID ARC OF CONTACT AND THE RESULTING CHANGE IN WEB TENSION. 